HLB – The Easiest Way to Create An Emulsion

Article by: Kelly Dobos

As a cosmetic chemist you will undoubtedly be asked to make products that require you to combine materials that aren’t easily compatible. Fortunately, there is a system that can help you get started.

Cosmetic Emulsions

Emulsions are one of the most common forms of cosmetic products. You find them in skin lotions, make-up, and even hair products. By definition an emulsion is a dispersion of two or more immiscible materials, where one phase, also know as the internal phase, is dispersed in the continuous or external phase. Cosmetic emulsions are classified as oil in water (O/W), water in oil (W/O) and water in silicone (W/Si). Multiple emulsions such as oil in water in oil (W/O/W) are also possible. Oil in water emulsions are the most common due to preferable cost and light skin feel.

In order to create an oil in water emulsion (one that remains stable for a long enough time), work must be done to overcome the interfacial tension between the two phases. This can be achieved by mixing; however mixing even at very high rates is not enough to provide long term stability. An emulsifier or combination of emulsifiers is needed to stabilize droplets of the dispersed phase. For example, simple oil in vinegar salad dressings will separate rapidly without the use of an emulsifier like mustard.

Using Surfactants

In this industry, we use surfactants to create emulsions. Surfactants are molecules that have a hydrophobic (oil soluble) and an effective hydrophilic (water soluble) portion. They act as emulsifiers by significantly lowering the interfacial tension and decreasing the coalescence of dispersed droplets.

HLB Formulating

Figuring out what surfactant to use for any specific formula will be a challenge you face as a cosmetic chemist. There is a great deal of research on surfactants and their behavior. But studying the thermodynamic equations and phase diagrams associated with surfactants can be a daunting task, not to mention the number of surfactants available to the formulator is vast. Luckily for us, William C. Griffin developed a way to streamline the selection of surfactants by utilizing the ratio of the hydrophobic to the hydrophilic portion of the molecule. This method is referred to as the HLB (Hydrophile Lipophile Balance) method. Griffin first presented this method at meeting of the Chicago Chapter of the Society of Cosmetic Chemists in 1949 and it is still widely used today. He published the method shortly there after.1 (A bit of trivia for you, the Chicago Chapter was the first chapter formed in Society of Cosmetic Chemists)

The HLB method applies to nonionic (uncharged) surfactants but attempts have been made to broaden the concepts to other surfactant types including silicone surfactants. And using the HLB system to create emulsions is quite simple. All you have to do is calculate the HLB number of your surfactant, then the Required HLB for the oil phase and match the two numbers.

Determining the HLB of a surfactant

A typical nonionic emulsifier (e.g. Laureth-4) contains an ethylene oxide groups or polyhydric alcohol hydrophilic portions with a fatty alcohol hydrophobic portion. The HLB for a nonionic surfactant can be calculated as follows:

HLB = Weight % Hydrophile/5

Example 1: HLB calculation for Laureth-4

Molecular weight of ethoxylate portion = 176

Molecular weight of lauryl alcohol = 186

Wt. % Hydrophile = (176/(176+186)) x 100 = 48.6%

HLB = 48.6/5 = 9.7

Based on the calculation, surfactants with high HLB values will be more water soluble and those with low HLB values are more oil soluble. Division by 5 just allows for a compact, easy to use scale. The calculation is simple, but you won’t usually have to figure it out since most surfactant HLB values are readily available through literature references and surfactant suppliers.

Calculating HLB of oil phase

Each lipophilic ingredient in the oil phase has its own required HLB. These required HLB values are determined experimentally, however a method utilizing solubility parameters has been proposed by Vaughan and Rice.2 Required HLB values for some common oil phase ingredients are available to the formulator in literature. The Req’d HLB values are approximate and can vary by about ± 1 unit. It is also important to keep in mind that cosmetic emulsions often have complex oil phases with several components. The required HLB of an oil phase mixture can be calculated by first calculating the percent of the oil phase each ingredient contributes. This percentage is then multiplied by the required HLB for each of those ingredients and the results are summed.

Example 2: Calculation of required HLB for an oil phase mixture

The oil phase is 10% of the total formulation and consists of:

4% Shea butter, 40% of the oil phase. Req’d HLB of 8.

3% Jojoba oil, 30% of the oil phase. Req’d HLB of 6.5.

3% Sunflower seed oil, 30% of the oil phase. Req’d HLB of 7.

Total required HLB:

Shea butter contribution 0.4 x 8 = 3.20

Jojoba oil contribution 0.3 x 6.5 = 1.95

Sunflower oil contribution 0.3 x 7 = 2.10

Total Req’d HLB = 7.25

You can now select emulsifiers to match the required HLB of the oil phase and create an emulsion. A blend of high and low HLB surfactants is often used to achieve the desired value in part because of demonstrated effectiveness and efficiencies in packing at the interface. The HLB for the surfactant blend is calculated in same manner as the required HLB for a blend.

Example 3: Calculation of HLB for a surfactant mixture

The surfactant mixture is a 70/30 blend of Steareth-2 and Steareth-21.

Total HLB:

Steareth-2 contribution 0.7 x 4.9 = 3.43

Steareth-21 contribution 0.3x 15.5 = 4.65

Total HLB = 8.08

In order to match the HLB of a particular oil phase, it is easiest to set up a spreadsheet with the calculation and vary the percentages of each emulsifier in increments of 5% to find the right ratio.

Limitations of HLB

Although a very useful tool, the HLB system does have some limitations. For example additional water phase ingredients are not considered but still may impact the stability. The method also does not provide information as to how much surfactant is needed, but 2 to 4% surfactant is a good starting point to begin further optimization for stability. So it is important to keep in mind that the HLB system is not absolute in prediction of your formulations behavior, but a very good starting point for achieving emulsification.

151 comments

Christina

Hello

I am trying to make a sunscreen ( o/w emmulsion ). Do UV filters e.g. Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine or Ethylhexyl Methoxycinnamate have an HLB value ? Are UV filters included in the calculation of the required HLB?

Hi.. my name is ryan. i am trying to make a blend of pine and citronella oil in water emulsion.
the formulation i use is 10% of emulsifier (abt 6mL) nonylphenol-9 (HLB-14), Citronella oil 35mL (HLB 12.6), Pine oIl 25mL (HLB 16) and water.

the process,
1. I mix both oil, and blend it for few seconds using normal hand blender, and then pour in the 10% (6mL) and blend it again for few seconds

2. i started pouring in water slowly until i get a thick white emulsion, before adding about 1/4 tbsp of thickener (CMC).

3. I poured the whole thing into a juice blender so that i can get higher RPM, and keep adding in water up to 500mL, and transfer to a liter Jar where i added another 500mL of water.

4. the whole solution appears milky white and thick. and i thought i managed to get a perfect emulsion

5. the following day, to my surprise, Creaming happen or white fluid float on top while the rest on the bottom of it I believed is water. This means my emulsion is not stable.

I need help on whats wrong and what can be done to make it right ! PLEASE HELP

Trying to make an oil-in-water emulsion and need general guideline on minimum proportion of emulsifier to dispersed phase. From what I’ve noted, it seems that 7-10
% emulsifier based on the dispersed (oil) phase is about as low as one can go depending on the oil, emulsifier, agitation, etc., to have reasonable stability. Is this reasonable?

Thanks Kelly, My application is for an industrial use where we’re trying to make a storage stable emulsion of base mineral oil in water with an “actives content” (oil plus emulsifier) of ca. 50% by weight in the continuous water phase. So far, about 10% emulsifier based on oil weight seems to work okay.
Thanks again for the feedback. Larry

hi
I want to make oil in water emulsion and i have : xantangum / guargum / acassia / resingum / vegetebel oil (sunflower) / oil essens / pectin / lecetin / suger / mustard / titanium oxied and sure water !
how to make emulssion with above material ( 2 / or more ) that it became very very white and fluent . thanks

So if you want to create a water-in-oil emulsion is it that all you have to do is make sure your oil phase has a required HLB between 7 and 11 and that the emulsifier or blend of emulsifiers you use match that required HLB of between 7 and 11?

Does the difference between a water-in-oil emulsion and an oil-in-water emulsion only come down to the range (7-11 for water in oil, 12-16 for oil in water) of the HLB of the emuslifiers/required HLB of the oil phase that you use?

I want to make a water-in-oil emulsion, couldn’t find info on how to do so or how they differ from an oil-in-water emulsion until I came across info on the HLB system, is it really that simple? Am I missing anything?

Hi Christina
Here is a link a much more detailed write up of the HLB by none other than Bill Griffen himself. http://www.firp.ula.ve/archivos/historicos/76_Book_HLB_ICI.pdf
It’s worth noting that a water in oil formula is hard to stabilize with the HLB method alone and there are modern polymeric emulsifiers that help. Electrolytes like magnesium sulfate are also added to the water phase to assist in stability and homogenizing to reduce droplet size of the oil phase. Hope this helps.

so if I’m reading the link to the ICI packet right…I have an emulsion I’m trying to make which is a oil in water emulsion with 1% solid castor wax and 48% paraffin oil….I am to heat the oil and melt the wax into it…add an emulsifier blend(?) and then heat water to 15degrees over the melt pt of the wax and slowly add the hot water to the oil/wax/emulsifier blend under propeller mixing then after addition slowly start cooling and should get an o/w emulsion? everything I’ve tried has given me a w/o emulsion. Procedure lists sorbitan trioleate at <1% which is odd as its a low HLB emulsifier….no other emulsifier is listed???? omitted by mistake/purpose???

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Christine
I was unable to find a published value when searching, but you should be able to perform a calculation as noted or above or contact the supplier as they should have this information readily available.

Hi there!
I am very new to this and am wanting to make a saop spray for my plants. I use stearyl alcohol to emulsify my oil and soap base; and it works quite nicely. However that is the concentrate. When I add 1oz of concentrate to 1gal of water, I have to constatly shake as I’m spraying. Is there anything that would help me create a stable emulsion with these ratios of oil:water? Thank you so much for you any help that is able to be offered.

Stearyl alcohol is not an emulsifier by itself… it can be a co-emulsifier and help provide structure in creams and lotions. You should consider selecting a combination of surfactants that match the HLB of your oil phase to emulsify.

HI, COULD SOMEONE HELP ME DO Sodium laureth sulfate, TRANSPARENT LIQUID SOAP, HE USED lauryl alcohol 7 MOL HLB 12.3 sulfonated I HAVE BUT I CAN BE THE AROMA emulsify TURBIO ANY COMMENT THE GREETINGS agradesco.

I’m pretty new to this field and I need help. Now i understand how to calculate the HLB of oil phase and the required HLB of surfactants phase. One question though is what happens if the HLB of surfactants is much greater than required HLB of oil phase ? Is it still going to work? Or do they have to match the number to have stable emulsion?

Hey there, I assume you haven’t gotten an answer, trying to help you here if I can. I have followed this person’s teaching’s for the last year or so, she’s very well known as a cosmetic chemist. Perhaps you’ve heard of Susan J. Barclay? her blog, Point Of Interest! is amazing, I almost guarantee you could likely find your answer there. She will even assist but have a flip through the myriad of posts. It’ll help, I’m sure. She’s all over Youtube as well.

The HLB of the emulsifying surfactant ”must” be very near the one you need. If it is too low or too high it will not work. But if you use two or three emulsifiers of different HLB, then you can do a mixture of them to have the right HLB you need within a range of HLB. Then you will have more tolerance of HLB deviations and better results.

How do you calculate the following quantities… seem to be stuck. Anybody have an idea?
A 35% Polyoxyethylene (20) oleyl ether (HLB 20) and 65% Polyoxyethylene (2) cetyl ether (HLB 5) was found to be optimal for a particular emulsion system.
What quantities of Sorbitan monoleate (HLB 4.3) and Polyoxyethylene sorbitan monopalmitate (HLB 15.6) should be used to stabilize this system.

The HLB of the POE 20 oleyl ether is actually about 15.6 and the HLB of the POE 2 cetyl ether is 5.6, so these are very close to the two alternate materials. I would suggest trying the same original ratio (35/65) and see how it does. Because the SMO is slightly lower than the POE 2 cetyl ether, you may have to shift this ratio slightly toward the POE SMP (40/60). HLB is not an exact science, though, so try a few blends and see what ratio gives the best particle size and stability.

Hello, I want to formulate a coQ10 cream regarding my research studies. My ingredients include coQ10, olive oil, cetyl alcohol, glyceryl monosterate, tween 80, span 80, propylene glycol and water. May I ask how to calculate 3 emulsifiers? Can I just calculate the quantity required for emulsifers of span and tween only? For calculation of oil base, that’s mean just consider calculation for olive oil and cetyl alcohol only not included propylene glycol? Thank you so much =)

when making oil-in-water emulsions using the HLB system the main idea is to lower the interfacial tension between the combined oil phase and the combined water phase. At the lowest interfacial tension it takes the least amount of mechanical energy to form the emulsion and it takes the least amount of surfactant to maintain emulsion stability. Using the general principles of the HLB system allows you to do a paper calculation of the theoretical required HLB of your unique oil phase in plain water and from that starting point you have the highest likelihood of success. I worked for Mr. Bill Griffin at ATLAS and ICI and for years taught the HLB system to our customers. I know from personal experience what a time saver applying the HLB system can be. For more information on HLB I suggest going to the CRODA website. The current CRODA company is the “keeper of the flame” on HLB and can provide you with a list of required HLB’s for most of the common cosmetic ingredients. HLB theory is also very successfully applied to the crop protection industry and to many industrial applications.

Hello…
If I want to stable emulsion of 20% toluene in remaining water using non ionic surfactant (combination or single)
Then how can calculate reqired HLB for toluene (oil) from their structure without experiment for only prediction

is the calculation will be the same for multiple emulsion w/o/w. do i have to calculate for primary w/o first and then for secondary o/w later to get the desired HLB for multiple emulsion. or it has its own calculation?or i can just use surfactant with necessary value of HLB for both as there are no mixture of surfactant in both primary and secondary emulsion. thank you

Dear,
I have done several trial & error but finally couldn’t get clear/transparent emulsion.I donno where the problem is?Required HLB for oils & Hlb of my surfactant all is maintain somehow in my little knowledge.But still solution become milky/to cloudy.I am trying to mix some of my essential oil blend like(Tea-tree,thyme, eucalyptus,cardamom, cinnamon,spearmint)to purified water to get a clear solution without using any alcohol. But always my solution become milky even oil & water mixed properly.Could anyone suggest some way to come out form the error?

You can search for published values or determine experimentally. To determine experimentally you would prepare emulsions with surfactant blends from high to low HLB values and the one that is most stable would assigned as the required HLB.

i want to make a stable emulsion from water(that some salts are solved in it)and vaseline(petroleum jelly)
which kind of emulsifier is suitable for it?i use of GMS but it was separated after some minute,however is it posible that after solidification of cream and remelting it i have a permanent emulsion?

So… if you calculate the required HLB of an Oil Phase and the result is around 3-8, the emulsion will be an w/o.
And if you calculate the required HLB of an oil Phase and the resulst i 9 or above, the emulsion will be an o/w.

I have some questions to grit or small particulate that will go away upon a little rubbing in the final product. Would this be a for of flake that is a fall out in the emulsion or is this a solid particle film that could be forming in a formula?

We are currently using polyglyceryl-3-diisostearate as well as glycerin.
Oils: Mineral Oil, Cream Petro, Synthetic Beeswax which accounts for about 50% and then water is approximately 30%. Any help/insight would be greatly appreciated!

Dear Kelly,
Could you kindly help me in how to make a stable silicon emulsion and a stearic acid emulsion using a 2 stage homogenizer?
Thanks in advance and congratulations for your article.
Charlie C.

How to get an o/w emulsion?
If oil phase HLB required is 7.2, and you ad a high HLB emulsifier (15.5) and and low HLB emulsifier (4.4) in a ratio that is 7.2, what type of emulsion do you get? I thought unless HLB was > 10 (or there abouts) that you’d get a w/o

You are correct, lower HLB surfactants (4-6) are W/O emulsifiers but other formulation factors like the size of the oil phase can effect formula type. You can simply test what type you have by trying to dilute the final product with water. A W/O does not dilute while a O/W would/

While it looks like your HLB is balanced, that’s quite a lot of emulsifier. Start with 2 to 4%. Also, is glycerin the only component of your external phase? If so the HLB method may not be a good predictor for stability.

You would need to know the structure of your surfactant, and keep in mind, HLB applies to ethoxylated nonionic surfactants. I’m not familiar with biosurfactant structures, so I don’t know whether the HLB method applies.

Thanks so much.
I want to ask one question:
How i can prepare an EC of mineral oil(raw liquid parrafin oil)?I know some emulsifiers can use for it but with high using level(about 8%-10 %).I want to use a suitable emusifier with lower usage than it.
regards
Abbasi

Hi George,
By the looks of it you are trying to create a w/o formulation. These are very tricky formulations to produce with only ethoxylated emulsifiers. Typically, waxes are added to the oil phase to help stbailize these types of emulsions and homogenization is a must. You may want to adjust your oil phase by adding oils with higher required HLBs and try making a o/w emulsion before attempting a w/o with this method.

i know that it is better to put some waxes… but i felt that the cream is thick enough due to the large amount of SPAN 60 WAX …
still i don’t want to do O/W cream.. inversely, i’m insisting on W/O creams… if u can help me in this .. because till now none of my formulas was stable at 50 Centigrate for more than 48 hours …( the oily phase begine to separate !!!! )

your stability failed at elevated temperature because of the melting point of the fatty portion of the emulsifier. At 50C the high HLB surfactant has a little shrinking of the EO chain (makes it a slightly lower HLB) and you have to remember that heat is energy and the surfactants start to want to “dance” away from their partners.
The most simple fix is to add some cosmetic polymer to the water phase. Something like one of the carbomers from Lubrizol or Structure Solanace from AxoNobel (formerly National Starch). Another thing to remember is to continue stirring down through the set point. This means to stir down below 30C. The reason for this is if you have any crystalline material like fatty alcohol you want to make sure that it has a chance to start to re-crystalize and for the liquid gel networks around the dispersed droplets of the oil phase

My own view is that making successful emulsions is more of an art than a science. My first emulsion, looking back on it, was actually a butter: it contained 25% lipids, of which 15% was shea. It had a salmon colour because of the green tea extract in it. I thought it was a failure, but got demands to make more from test customers who really loved it. More lately I’ve been more into using desert plant bioactives.

1) Simple mixing with an impeller blade is all that is need to perform the testing.
2) As mentioned above, there is no method for calculating the quantity of surfactants needed. You must determine the quantity experimentally.
3) In general, you slowly add the expected internal phase to the expected external phase. I do not have a formal procedure to share.
4) In general, the external phase should account for >= 26% of the total composition for traditional emulsions based on geometrical consideration of hexagonally packed spheres.

Dear kelly, I just want to know the process of how to make different w/o and o/w emulsions of organic solvents like toluene, hexane, benzene, cyclo hexane etc.. but my problem is that 1) how to set up apparatus for emulsions preparation?
2) how to calculate required qty of surfactant ?
3) what will be mode of addition of compounds ie water phase first or oil phase first….pls give me experimental procdure if possible. 4) I want some std qties for w/o and o/w emulsions of organic solvents as oil phase?
expecting kind reply

Dear Jagat,
You must experimentally determine you required HLB as mentioned about by observing stability with the oil phase and various surfactant combinations to achieved different HLB values. We cannot help until you have done this.

sir good morning
sir i have read your all suggestion,its very impressive. sir actually iam taking 40% essential oil and rest is water and excipient.so please guide me to formulate the cream. hope i wil get some detail idea.yours faithfully

Hi Alicia,
I would use glyceryl stearate, lecithin can have some draw backs with stability my opinion. 7% emulsifiers seems like a high starting point even for your large oil phase. I would place range of emulsifier levels on stability to determine an optimum level. -Kelly

I saw a rough ratio of 7:1 (oil phase: emulsifier) recommended somewhere in the archives here.. which would mean I require approx 7% total emulsifiers as my oil phase makes up 49% of the total formulation

Thank you Kelly for your response, much appreciated!
I am using stearic acid and/ or stearyl alcohol for the high HLB component. From a formulator’s point of view would you recommend glyceryl stearate OR hydrogenated lecithin for the lower value surfactant?
trying to go “nature-identical” as much as possible with the products..but saying that would very much like to get the texture beautiful and stable!

Hi Alicia,
You are correct, you would need a combination of low and high HLB surfactants to emulsify using the HLB system. Or you can try creating soap based emulsion by neutralizing the stearic acid with a base like triethanolamine. -Kelly

I’m just learning about the HLB system and have been trying to perfect the texture of a cream. It has equal proportion of water to oil, has a little grittiness and just a small amount of water separating out. Have done all calculations and come to a total required HLB of 8.36…
And now to select the emulsification system. Would you mind clarifying how I would achieve this with using what I have access to: Stearic acid and stearyl alcohol, both with HLB around 15? Do I need to combine with a low HLB value emulsifier like lecithin (4)? Thanks for your advice!

sir would you like to give me the protocol if u have , how to proceed further for the determination of hlb of some essential oils. if u have some research article then plz send me some of them so that i can proceed further with u r guidance.
regards jagat jyoti sahu
waiting for u r reply

Hello Jagat,
You will need to experimentally determine the required HLB for your oil. You create emulsions with a combination of high and low HLB emulsifier at varied ratios but the same total concentration to test different HLBs. The required HLB is then taken from the emulsion that remains most stable.

Just wonder how to interpret/decide which emulsion remains the most stable? I have set the surfactant to be 3% (parenteral formulation).

Then, all the resulting emulsion seems to be the same. Separation of oil and water has taken place. The oil will immediately float back to above after i shaken the emulsion (although the oil did dispersed into the water when i shaked the emulsion at 1st). However, i do see droplets of oil. They do not aggregate to form a bigger droplets. Should i just proceed with other surfactant? Because the same situation has taken place for the 3rd kind of surfactant’s mixture. Thanks for the advice. =)

i want to know how to calculate the hlb value of cetronella oil.but first point is selection of surfactant.but how we wil select surfactant. we have oil percentage around 83 and water the rest. so kindly tel me on what basis i wil select the surfactant blend

Hi Nancy,
There are no rules on how much emulsifier you need , a good starting point is 2%. Placing various levels on accelerated stability testing can help you to select the optimum level for a particular oil phase.

Hi Nancy,
There aren’t many published values for W/O required HLBs, this maybe due to the reason that most cosmetic formulators favor O/W due to cost, ease of stabilization, etc. You may be able to find some if you search for a specific oil and it’s required HLB in W/O systems. Hope this helps!

Hi Nancy,
That’s a great question! The HLB for oils in O/W vs. W/O is different. Low HLB emulsifiers are used to create W/O formulations, and following the Bancroft Rule the phase in while the emulsifier is most soluble constitutes the continuous phase. So is the emulsifier HLB is low, it would be matched to an oil phase with a low required HLB. For example in O/W mineral has a required HLB around 10 and for W/O it is closer to 5.

Bill,
The HLB system is still a great tool for the formulator and one the I use frequently. The beauty is in the ease with which it can be used. As a big enthusiast of cosmetic science, it’s an honor to hear from you! Thanks so much, Kelly

Dennis’ comments are a bit amusing in one sense of the word because slide rules were still in use then. Yes, we recognized some of the faults of the system and these were outlined in my thesis for a Master’s Degree in 1955 which, of course, was not published.

It was my unimaginable pleasure to wander through a current emulsion innovation lab at the Croda plant a year or so ago and the advances on all sides was amazing beyond belief. Of course, the truly amazing thing is that the basic premise is still being used and taught so long after its development. Doubly impressive since my retirement happened thirty-one years ago.

Cheers, and may you have as much fun as has been my good fortune in life – and without scads of money.

I know what I’m going to say here is provocative and sacrilegious, but this whole system seems somewhat antiquated and akin to the slide rule. I think modern formulation requires more flexibility and has available to it more effective tools. Using DOE and polymeric emulsifiers we can create better products faster and discover more unexpected combinations than using these HLB calculations, which don’t account for formula aesthetics or product perception. Even using this system it’s still an iterative process to achieve the look and feel of the product you want.

Certainly, you make an excellent point. There are more rigorous ways of making an emulsion. But this kind of background information is still useful in concept and the method (while antiquated) can still be used effectively.